(a) Field of the Invention
The invention relates to a pick-up apparatus and method and, more particularly, to an image recognition in a pick-up apparatus and a pick-up method which are used during a mounting step for packaging semiconductor devices.
(b) Description of the Related Art
In a mounting step for semiconductor devices which occurs during packaging thereof, a multiplicity of semiconductor pellets or chips are disposed in an aligned arrangement as divided from a semiconductor wafer. The semiconductor chips are subjected to an image recognition before pick-up in order that only non-faulty chips be picked up for mounting or packaging.
Specifically, a multiplicity of chips disposed in an aligned arrangement on an X-Y plane are viewed one by one by a camera, and a chip which is located within the field of view of the camera is subjected to an image processing step. During the image processing step, an image data of a chip, which is obtained on the basis of a video signal from the camera, is stored in a frame memory, and an image recognition is applied to such image data to determine if a particular chip is faulty or non-faulty. The decision to determine whether a chip is faulty or non-faulty is carried out on the basis of the presence or absence of the chip itself at that position, the presence or absence of a fault in the appearance such as a notch, and the presence or absence of a faulty mark applied to the chip surface. After completion of the image recognition, a chip which is determined to be non-faulty is picked up by a devoted jig called "collet", which applies a vacuum suction to the non-faulty chip.
A conventional operation will be described below in which a single chip is placed in the field of view of a camera and then subjected to an image recognition in order to allow non-faulty chips to be sequentially picked up.
Initially, chips are disposed in a matrix on an X-Y plane so as to be aligned in X and Y directions. A particular chip which is placed in the field of view of a camera is viewed at a pick-up position by the camera for an image recognition. Based on the presence or absence of a faulty mark etc., a decision is made if it is faulty or non-faulty. When a decision is made that the particular chip is non-faulty, the location of the particular chip is finely adjusted at the pick-up position, and is picked up subsequent to the completion of the adjustment.
When the pick-up operation is completed, a next chip located adjacent to the first mentioned particular chip is moved to the pick-up position through a predetermined one pitch move so as to be viewed by the camera within the field of view thereof. The second chip is again subjected to an image recognition to determine if it is faulty or non-faulty, and if the next chip is determined to be non-faulty, the location thereof is finely adjusted at the pick-up position in a similar manner as mentioned before, whereupon the next chip is picked up. On the other hand, if the chip is found to be faulty, no pick-up operation takes place for this chip, and instead, another one pitch move takes place for the X-Y plane to bring the succeeding chip to the pick-up position so as to locate the succeeding chip in the field of view of the camera for the image recognition.
In the manner as described above, a sequence for operations including an image recognition of a chip located within the field of view of the camera, a decision made on the basis of a faulty mark etc. to determine if the chip is faulty or non-faulty, a pick-up of a non-faulty chip and one pitch move for a succeeding chip is repeated for each of the chips arranged in the matrix on the X-Y plane.